1. Field of the Invention
The invention relates to computer communications and more particularly to communications over a radio frequency channel.
2. Description of the Related Art
Computer communications are developing at a hectic pace. In the past, communications between computers was primarily done over telephone lines, be they dedicated when higher speeds were desired or conventional switched lines when lower costs were desired and lower speeds were acceptable. Recently, a revolution started in computer communications. This was the advent of computers communicating over radio frequency channels. Examples include desktop computers connected over a wireless area network and laptop computers connected to or including cellular telephones to allow conventional modem communications over a cellular link. The use of the radio frequency channels has allowed greatly improved flexibility and location of the computer, be it a desktop or a laptop unit. No longer is the user required to keep the computer within wires length distance of the appropriate connection. The computer is free to be moved to the desired physical location, and indeed in the case of a laptop computer could even be travelling along in an automobile. In addition, this great flexibility allows greater communications when laptop and notebook computers are used. The user may call over the cellular link from any location, even if no telephone lines are readily available. Further, the capabilities are being dramatically increased as more and more radio frequency channels are being developed and more protocols are being provided. Each of these particular channels and protocols have certain advantages and thus the user is free to choose depending upon location, available services and desired capabilities.
However, one common factor has become quite apparent in these early days of radio frequency communications using computer systems. This common factor has been that the computer generates a great deal of radio frequency interference or RFI. While the computers are generally sufficiently noise free that they may pass applicable standards, such as FCC Class B for consumer use, it has been determined that even with these relatively low noise computer systems, the RFI levels are still sufficiently high, particularly at the desired radio frequencies, to make reception, and in some cases transmission, of signals over the radio frequency channels problematic. In part, this is because the antenna is typically located closely adjacent the computer. Thus the antenna is directly in the field of the primary interference source. In the past this would have been remedied in a simple fashion simply by having the antenna installed at a remote location sufficiently far from the interference source and running a cable, such as a co-axial cable, between the antenna and the transmitter and receiver. However, this again brings back the limitations of cables and all the problems associated therewith. The computer user must locate the computer, place the antenna in the desired location and string a cable between the two. This is inconvenient in desktop installations and basically impractical in many laptop environments. Therefore it is desirable to be able to have the improved radio environment where the antenna is located at a sufficient distance from the computer to remove it from the high noise environment and yet it is also desired that the communications between the antenna and the computer be wireless.
Further, as noted above, there are numerous radio frequency channels and protocols being developed. It would be desirable to not only provide this remote antenna capability, but also to allow the capability to utilize numerous of the radio frequency channels and protocols with essentially the same unit, thus reducing costs.